| marine (taeniura lymma) and freshwater (himantura signifer) elasmobranchs synthesize urea for osmotic water retention. | the objective of this study was to elucidate whether the marine blue-spotted fantail ray, taeniura lymma, and the freshwater white-edge whip ray, himantura signifer, injected with nh(4)cl intraperitoneally would excrete the majority of the excess ammonia as ammonia per se to ameliorate ammonia toxicity despite being ureogenic. to examine the roles of urea and the ornithine-urea cycle, experimental fishes were exposed to salinity changes after being injected with nh(4)cl. the ammonia excretion ra ... | 2013 | 15957115 |